Technical Field
The invention relates to a device for the cutting and suctioning of tissue from the human body or animal body, particularly for application in vitrectomies, in cases of retinal detachment, etc. The device includes an outer tube and an inner tube which can slide concentrically inside the outer tube in both directions with minimal play, wherein the outer tube is closed on the free end thereof, and has a lateral opening with at least one inner cutting edge near the free end. The inner tube is open on the free end and has an outer cutting edge at this position. The cutting edges work together with a cutting function when the inner tube is slid.
In principle, the invention relates to a surgical cutting instrument for the removal of tissue. By means of the instrument, it is possible to cut tissue on and/or in the body and suction out the same from and/or off of the body. Concretely, the invention can relate to a very special cutting instrument by means of which it is possible to destroy and/or break up the vitreous humor in the eye, and remove the same from the eye, as part of a vitrectomy. In addition, it is possible to remove blood, coagulated blood, and connective-tissue-like alterations and regions of the retina resulting from retinal peeling by using this instrument.
Description of Related Art
By way of example for prior art, reference is made only to U.S. Pat. No. 5,630,827, in which a cutting instrument suitable for vitreous humor operations is known. The cutting device is open on the proximal end. On the distal end [thereof], it has a closed outer sheath which has multiple openings near the closed end. The openings each form a slot and enable vitreous humor tissue to penetrate into the lumen of the outer sheath. In addition, the cutting instrument has an inner sheath which is arranged concentrically to the outer sheath, and which is accommodated in the outer sheath in a manner allowing longitudinal movement, and which has a sharp edge on its distal end for the purpose of cutting the vitreous humor when the inner sheath is slid forward.
In the case of the device known from U.S. Pat. No. 5,630,827, it is essential that the inner tube has an open, peripheral edge on its free frontal end which serves as the cutting edge. This edge is accordingly shaped and/or sharpened. The outer edge region bears the cutting function, and consequently from this point forward, the document discusses an outer cutting edge of the inner tube. This outer cutting edge works together with one or more inner cutting edges of the outer tube, such that tissue which has pressed into the device is cut and/or separated upon the cutting edges mutually sliding past each other. Next, the tissue can be suctioned out of the interior of the device—more precisely stated, through the inner tube.
A cutting instrument characteristic of the class is likewise known from WO 98/52502, for the purpose of removing vitreous humor tissue. A closed outer sheath is included at the distal end of the instrument, and has multiple slits near the distal end through which the vitreous humor tissue can enter. An inner sheath is included concentric to the outer sheath, and can move longitudinally, having a sharp edge on its distal end for cutting the vitreous humor tissues which have penetrated into the tube. In addition, a drive mechanism is included for the inner sheath, by means of which it is possible to move the inner sheath with its cutting edge in the region of the distal end past the slit arranged in the outer sheath, such that a cutting process is realized at this point in both directions.
However, the known devices of the type which characterizes the class are problematic in practice for two reasons. First, the work speed [with the instrument] is limited by the frequency with which the inner tube is moved back and forth, particularly with its outer cutting edge moving past the inner—or the inner cutting edge moving past the outer—tube. As such, only a certain amount of tissue can be cut with each stroke of the inner tube, whereby the throughput is limited by the maximum frequency.
In addition, it is disadvantageous that the known device generates very significant pressure and/or vacuum fluctuations in the eye, particularly as a result of the fact that the opening or openings which serve to provide suctioning is/are alternatingly completely closed and completely open according to the position of the inner tube. As a result, an alternating vacuum is created in the body and/or eye which is essentially impossible to compensate. The resulting significant pressure fluctuations can lead to damage to the eye.